title: Role of protein farnesylation events in the ABA-mediated regulation of the Pinoresinol-Lariciresinol Reductase 1 (LuPLR1) gene expression and lignan biosynthesis in flax (Linum usitatissimum L.).
abstract: A Linum usitatissimum LuERA1 gene encoding a putative ortholog of the ERA1 (Enhanced Response to ABA 1) gene of Arabidopsis thaliana (encoding the beta subunit of a farnesyltransferase) was analyzed in silico and for its expression in flax. The gene and the protein sequences are highly similar to other sequences already characterized in plants and all the features of a farnesyltransferase were detected. Molecular modeling of LuERA1 protein confirmed its farnesyltransferase nature. LuERA1 is expressed in the vegetative organs and also in the outer seedcoat of the flaxseed, where it could modulate the previously observed regulation operated by ABA on lignan synthesis. This effect could be mediated by the regulation of the transcription of a key gene for lignan synthesis in flax, the LuPLR1 gene, encoding a pinoresinol lariciresinol reductase. The positive effect of manumycin A, a specific inhibitor of farnesyltransferase, on lignan biosynthesis in flax cell suspension systems supports the hypothesis of the involvement of such an enzyme in the negative regulation of ABA action. In Arabidopsis, ERA1 is able to negatively regulate the ABA effects and the mutant era1 has an enhanced sensitivity to ABA. When expressed in an Arabidopsis cell suspension (heterologous system) LuERA1 is able to reverse the effect of the era1 mutation. RNAi experiments in flax targeting the farnesyltransferase β-subunit encoded by the LuERA1 gene led to an increase LuPLR1 expression level associated with an increased content of lignan in transgenic calli. Altogether these results strongly suggest a role of the product of this LuERA1 gene in the ABA-mediated upregulation of lignan biosynthesis in flax cells through the activation of LuPLR1 promoter. This ABA signaling pathway involving ERA1 probably acts through the ABRE box found in the promoter sequence of LuPLR1, a key gene for lignan synthesis in flax, as demonstrated by LuPLR1 gene promoter-reporter experiments in flax cells using wild type and mutated promoter sequences.
authors.affiliation: Laboratoire de Biologie des Ligneux et des Grandes Cultures (LBLGC), UPRES EA 1207, Antenne Scientifique Universitaire de Chartres (ASUC), Université d'Orléans, 21 rue de Loigny la Bataille, F28000 Chartres, France.
authors.forename: Cyrielle
authors.initials: C
authors.lastname: Corbin
authors.forename: Cédric
authors.initials: C
authors.lastname: Decourtil
authors.forename: Djurdjica
authors.initials: D
authors.lastname: Marosevic
authors.forename: Marlène
authors.initials: M
authors.lastname: Bailly
authors.forename: Tatiana
authors.initials: T
authors.lastname: Lopez
authors.forename: Sullivan
authors.initials: S
authors.lastname: Renouard
authors.forename: Joël
authors.initials: J
authors.lastname: Doussot
authors.forename: Christelle
authors.initials: C
authors.lastname: Dutilleul
authors.forename: Daniel
authors.initials: D
authors.lastname: Auguin
authors.forename: Nathalie
authors.initials: N
authors.lastname: Giglioli-Guivarc'h
authors.forename: Eric
authors.initials: E
authors.lastname: Lainé
authors.forename: Frédéric
authors.initials: F
authors.lastname: Lamblin
authors.forename: Christophe
authors.initials: C
authors.lastname: Hano
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D019597:Flax / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression / Q000235:genetics / Q000502:physiology; D017705:Lignans / Q000096:biosynthesis*; D017368:Protein Prenylation / Q000235:genetics / Q000502:physiology
chemical_list: D017705:Lignans; D000040:Abscisic Acid
keywords: (+)-Secoisolariciresinol; Abscisic acid; Enhanced Response to Abscisic Acid 1 (ERA1); Farnesyltransferase; Lignan; Linum usitatissimum; Pinoresinol–lariciresinol reductase (PLR)